Former All-Pro running back Larry Johnson is accused of beating the living daylights out of a man ... who later allegedly told police, "This ni**er is going down" -- referring to Johnson.
In a civil lawsuit, filed last week, the alleged victim -- John Phillip Graney -- claims he was leaving a Miami Beach party in May when Johnson punched, tackled, and kicked him ... leaving Graney "beaten and brutalized."
Miami Beach police responded, and according to the official report ... Graney told an officer, "This ni**er is going down. He needs to learn a lesson, it's going to cost this prick."
TMZ obtained photos of Graney's alleged battle scars ... and according to the suit he suffered cuts to his face and ear, bruised chest and knees ... 3 herniated discs, and a torn rotator cuff.
Graney claims the whole fight was unprovoked. As for using the n-word ... his attorney Jonathan Davidoff says Graney is not a racist and "does not recall making those statements."
Johnson denies all the allegations in the lawsuit -- and his attorney tells TMZ, "This is a straight extortion claim designed to seek money."